Category Archives: Ultrasonics

Magnetostrictive Ultrasonic Cleaning Succeeds Where Less Powerful Piezoelectric Ultrasonics Fail

Case Study: nPB (N-Propyl Bromide) Replacement

N-Propyl Bromide (nPB or 1-Bromopropane) is a toxic solvent often used in cleaning or vapor degreasing applications. As a suspected human carcinogen and proven animal carcinogen, it has been targeted by the U.S. Environmental Protection Agency for risk evaluation and the European Union has banned it’s use without authorization after July 4, 2020. It is clear that nPB use will soon be banned or greatly restricted and existing users are encouraged to look for a replacement.

Companies presently using nPB are searching for safe, economical and effective replacements for nPB and Magnus Engineered Equipment has been successful in assisting customers to replace nPB with less costly, non-hazardous chemistry while accomplishing the same or improved cleaning. The following is an example where Magnus Engineered Equipment helped a customer develop a cleaning process utilizing nPB and then further helped them replace nPB with non-hazardous, environmentally friendly chemistry.

Highly crosslinked polyurethane is one of the toughest and most durable polymers, and producers often mold this material into usable items such as wheels for roller coasters and skateboards, hoses and automotive suspension bushings. The molds can become contaminated and cleaning the molds is a difficult and time-consuming process.

MEE worked with a customer to develop a chemical cleaning process for their polyurethane molds (steel and aluminum). Previously, a media blasting method was utilized to clean the molds and the process required mold dis-assembly and up to 4 hours of blasting. Using MEE Powersonics, the world’s most powerful magnetostrictive ultrasonic cleaning technology, MEE was able to demonstrate mold cleaning in less than 5 minutes with no mold dis-assembly. (This result was not achievable with less powerful piezoelectric ultrasonic cleaning). With this success in hand, attention was directed at finding a safer chemistry. Powersonics coupled with Acrastrip chemistry by US Polychem was able to replicate the performance achieved with nPB. Acrastrip is a water-soluble, non-hazardous environmentally friendly cleaner that was designed to replace acetone, toluene, MEK, Methylene Chloride, Xylene, MIBK, NPB, Ketones, and other petroleum-based products. In addition, Acrastrip is HAPS free, biodegradable, non-flammable, non-toxic, pH neutral and recyclable.

A Polyurethane mold cleaned with powerful 20 kHz magnetostrictive ultrasonic technology and water-based Acrastrip cleaner

The cleaning tandem of MEE magnetostrictive ultrasonics and Polychem Acrastrip is one example of how MEE can assist customers who are looking to replace nPB with a safer, more cost-effective and quality cleaning operation. MEE Powersonics is the world’s most powerful ultrasonic cleaning technology and can often deliver successful cleaning where less powerful piezoelectric ultrasonics fail.

 

Are your Ultrasonics Powerful Enough?

Magnus Engineered Equipment (MEE) produces the most powerful ultrasonics for cleaning applications.  MEE manufactures ultrasonic transducers which operate at 20 kHz which is 25 times more powerful than the 40 kHz transducers supplied by other suppliers of cleaning equipment.  The transducers are made with continuously laminated magnetostrictive 20 kHz elements which deliver more uniform cleaning than the discretely mounted piezoelectric elements used in 40 kHz transducers.

Figure 1


Comparison of 20 kHz vs 40 kHz Ultrasonics with Household Aluminum Foil

Figure 1 shows the difference in cleaning power between the two types of transducers.  The 20 kHz transducer will perforate and tear the soft household aluminum foil whereas the less powerful 40 kHz transducers will only dimple the aluminum foil.

Figure 2 shows the difference in construction of 20 and 40 kHz transducers.  The weaker 40 kHz transducers are bonded to a thin stainless steel sheet to minimize the loss of energy from the piezoelectric elements.  The weak stainless can readily flex between the elements and thus transfer the energy to the cleaning solution.  This thin stainless steel sheet is prone to develop porosity and limits the 40 kHz transducer to a lifetime of 2-3 years.  The more powerful 20 kHz elements are continuously bonded to a thick stainless steel sheet which prevents porosity and greatly extends the life of the transducer.  The uniform bonding delivers a more uniformly sonicated cleaning solution which in turn delivers more uniform cleaning.

Figure 2

Polyurethane Mold Cleaning

Urethanes are an adhesive and will bond to aluminum or steel molds.  Over time, the molds used in the casting of urethane and polyurethane parts build up a residue and require cleaning.  Magnus Engineered Equipment (MEE) can provide a cleaning process wherein the molds are cleaned in less than 5 minutes and without any damage or distortion to the mold.  Dis-assembly of the mold is not required for cleaning.  Any size or weight mold can be cleaned with the MEE cleaning process.

In the past, producers of molded urethane parts would use an abrasive or grit blasting to clean the molds after casting.  This cleaning process caused the mold surface to become rougher which then made mold release and mold cleaning even more difficult.  These cleaning processes often required dis-assembly of the mold and many hours of effort to remove the surface contamination.  Using 20 kHz magnetostrictive transducer technology, MEE can provide a cleaning process which will clean the mold without dis-assembly, cause no harm to the mold, and will clean the mold in less than 5 minutes!

MEE manufactures and supplies the most powerful ultrasonic cleaning equipment for cleaning applications.  Unlike the commonly used piezoelectric transducers which operate at 40 kHz, MEE supplied magnetostrictive transducers which operate at 20 kHz and deliver ~25 times more cleaning power than piezoelectric transducers.  Higher power equates to more thorough cleaning, faster cleaning speeds, or both.  Figure 1 shows the cleaning power comparison between MEE’s magnetostrictive transducers and piezoelectric transducers.

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Figure 1 Magnus vs Competitor’s Ultrasonic Cleaning Power

 

Here are some photos of molds with polyurethane contaminant which were cleaned with the MEE process. 

Before Cleaning After Cleaning